WHO emergency guidance on the use of licensed Ebola vaccine during Bundibugyo virus disease outbreaks, 31 August 2026

Overview

This updated WHO emergency guidance provides recommendations on the potential use of Ervebo®, the only licensed Ebola vaccine, during outbreaks caused by Bundibugyo virus (BDBV). The document reviews additional animal, immunological and observational evidence assessed by the Strategic Advisory Group of Experts on Immunization (SAGE) and concludes that, although some findings suggest possible cross-protection against BDBV, the available evidence remains insufficient to determine whether Ervebo® provides clinically meaningful protection in humans.
The guidance outlines the benefits, risks and unknowns associated with off-label use of Ervebo® during the ongoing BDBV outbreak and recommends that the vaccine be used only within research protocols. It emphasizes the importance of rapidly generating robust efficacy data through a ring randomized controlled trial, maintaining proven outbreak-control measures, clearly communicating the unknown efficacy against BDBV, and accelerating development of BDBV-specific vaccines and other countermeasures.